In-Flight Performance of the ICON EUV Spectrograph.

We present in-flight performance measurements of the Ionospheric Connection Explorer EUV spectrometer, ICON EUV, a wide field ( 17 ∘ × 12 ∘ ) extreme ultraviolet (EUV) imaging spectrograph designed to observe the lower ionosphere at tangent altitudes between 100 and 500 km. The primary targets of the spectrometer, which has a spectral range of 54-88 nm, are the Oii emission lines at 61.6 nmand 83.4 nm. In flight calibration and performance measurement has shown that the instrument has met all of the science performance requirements. We discuss the observed and expected changes in the instrument performance due to microchannel plate charge depletion, and how these changes were tracked over the first two years of flight. This paper shows raw data products from this instrument. A parallel paper (Stephan et al. in Space Sci. Rev. 218:63, 2022) in this volume discusses the use of these raw products to determine O+ density profiles versus altitude.

Design and Performance of the ICON EUV Spectrograph.

We present the design, implementation, and on-ground performance measurements of the Ionospheric Connection Explorer EUV spectrometer, ICON EUV, a wide field (17° x 12°) extreme ultraviolet (EUV) imaging spectrograph designed to observe the lower ionosphere at tangent altitudes between 100 and 500 km. The primary targets of the spectrometer, which has a spectral range of 54-88 nm, are the Oil emission lines at 61.6 nm and 83.4 nm. Its design, using a single optical element, permits a 0°.26 imaging resolution perpendicular to the spectral dispersion direction with a large (12°) acceptance parallel to the dispersion direction while providing a slit-width dominated spectral resolution of R ~ 25 at 58.4 nm. Pre-flight calibration shows that the instrument has met all of the science performance requirements.

Collimated focal ratio degradation testing for highly multiplexed fiber systems-an improvement to a standard test.

A simple method for determining the focal ratio degradation of optical fibers has been developed. The method involves splitting the light from the test fiber and recording ring patterns that have traveled over two different, and known, optical paths. This new method will be valuable for testing many fibers as will be needed for new multiobject astronomical spectrographs.

Chemical method to increase extreme ultraviolet microchannel-plate quantum efficiency. II. Analysis and optimization.

Enhancement of the extreme ultraviolet quantum detection efficiency (QDE) of microchannel plate (MCP) detectors by use of a wet chemical method is examined. It is shown that the chemical process of ion exchange, in addition to physical processes that increase surface roughness and decrease surface density, augments the secondary electron emission coefficient, which in turn increases the quantum detection efficiency of the input MCP. The method has been demonstrated with nitric acid, acetic acid, or water used as the active reactant. By monitoring and optimizing the ion-exchange process, we achieved a 2.6-4.4 increase in the MCP QDE from 1216 to 304 A, respectively, with an absolute QDE of approximately 50% at 304 A.